William was born in Liverpool and relocated to Oldham when he was nine years old. His stage career includes portraying Toby Belch in Twelfth Night for the Royal Shakespeare Company, Valk in The Jail Diary of Albie Sachs, and the roles of Snawley and Tompkins in Nicholas Nickleby, performed in both London and New York. He also appeared as the Club Secretary in Comedians at the Old Vic Theatre, alongside the legendary Jimmy Jewel. In addition, Bill created and performed a one-man show based on the work of Brendan Behan.

On television, he played the Duke of Cleves in The Wives of Henry VIII, Sergeant Petty in The Case of the Frightened Lady, and Crookes in Strangers. His television credits also include appearances in Coronation Street, The Dustbin Men, Z Cars, When the Boat Comes In, Funnyman, Softly, Softly, Dempsey and Makepeace, and Brookside.

His film work includes roles in The Ploughman's Lunch, Cicero, Blood Beast Terror, and The Witchfinder General.